Core carrying mandrel



Jan. 7, 1969 H. A. BRUNNER ET AL 3,420,465

CORE CARRYING MANDREL Filed April 4, 1967 HANS A BRUNNER BENTON A.WHITEMAN w w THEIR ATTORNEYS United States Patent Claims ABSTRACT OF THEDISCLOSURE This disclosure relates to an expandable mandrel for carryinga tubular core wherein such mandrel has a supporting member providedwith a plurality of symmetrically arranged keyway means each havinginclined planar bearing surface means and each carrying an associatedtapered key which has a cylindrical core carrying segment fastenedthereto. The plurality of cylindrical segments are normally held in aretracted, i.e. reduced diameter, position by yieldable urging meanswhich acts axially along the elongated axis of such supporting memberand holding means which acts radially inwardly toward such axis. Boththe urging means and holding means are overridden to move the corecarrying segments radially outwardly into engagement with the insidesurface means of such tubular core upon driving such mandrel with asuitable drive means.

This invention pertains to a core carrying mandrel and more particularlyto an expandable mandrel for carrying a tubular core.

It has been previously proposed in copending patent application, Ser.No. 475,218, filed July 27, 1965, to provide a mandrel adapted to beused with a strip conductor coil making apparatus. Such previouslyprovided mandrel is constructed and arranged so that it is insertablewithin a tubular core and then expanded to firmly hold such core inposition during a subsequent operation wherein a strip conductor iswound on the core carried by such mandrel. The previously providedmandrel is comparatively expensive to produce and does not exert holdingforces which are uniformly applied in all directions against insidesurface means of an associated tubular core.

Accordingly, it is a feature of this invention to provide an improvedexpandable mandrel which is of simple and economical construction.

Another feature of this invention is to provide an improved expandablemandrel of the character mentioned which provides holding forces whichare more uniformly applied in a radial manner against inside surfacemeans of a tubular core to be supported thereon.

Therefore, it is an object of this invention to provide an improvedexpandable mandrel having one or more of the novel features of thisinvention as set forth above or hereinafter shown or described.

Other objects, uses, and advantages of this invention are apparent froma reading of this description which proceeds with reference to theaccompanying drawings forming a part thereof and wherein:

FIGURE 1 is a side view of the improved expandable mandrel of thisinvention and showing by dotted lines the position of a tubular core tobe carried thereon.

FIGURE 2 is an exploded perspective view particularly illustrating theconstruction and arrangement of the cooperating members which comprisethe expandable portion of the mandrel of FIGURE 1.

FIGURE 3 is a view on the line 33 of FIGURE 1.

FIGURE 4 is a sectional view on the line 44 of FIG- URE 3.

While the various features of this invention are hereina'fterillustrated and described as being particularly adaptable for providingan expandable mandrel adapted to be used with a strip conductor coilwinding apparatus, or the like, it is to be understood that the variousfeatures of this invention can be utilized singly or in any combinationthereof to provide an expandable mandrel for other uses, as desired.

Therefore, this invention is not to be limited to only the embodimentillustrated in the drawings, because the drawings are merely utilized toillustrate one of the wide variety of uses of this invention.

In the exemplary embodiment of this invention illustrated in thedrawings an expandable mandrel designated generally by the numeral 20 isillustrated. Mandrel 20 is suitably mounted for essentially frictionlessrotation on a right circular cylindrical rod end portion 21 of asupporting member 22.

Mandrel 20 has a freely rotatable support assembly designated generallyby the numeral 24 and comprising a cylindrical member 25 having athreaded outer surface shown at 26 and a central bore 27 which defines ablind hole in one end thereof. Support assembly 24 also has asleeve-like member 30 which is provided with threads 31 at its inner endwhich are threadedly engaged with threads 26 of member 25 to holdmembers 25 and 30 firmly fastened together.

Bearing means shown as a pair of spaced apart ball bearings, or thelike, each designated by the numeral 32 are provided at the terminal endof rod end 21 in spaced apart relation. Bearings 32 support assembly 24and hence mandrel 20 essentially in a cantilevered manner on rod end 21.

Bearings 32 are inserted in central bore 27 and the inner bearing 32 ispositioned with its outer race against an annular shoulder 25A in member25 and its inner race against a cap-like member 21A fastened at theterminal end of rod end 21. Bearings 32 are held in spaced apartrelation in any suitable manner and in this example a cylindrical sleeve33 is placed therebetween and in surrounding relation around rod end 21.

A split ring 34, commonly referred to as a snap ring, is installed in acooperating annular groove 34A provided in member 25. Another snap ring38, or the like, is installed in a cooperating annular groove 38A in rodend 21. Snap rings 34 and 38 are used to pr vent relative axial movementbetween rod end 21 and support assembly 24 with bearings 32 installed inposition.

Thus, it is seen that support assembly 24 and hence mandrel 20 is freeto rotate in a frictionless manner on bearings 32 while being securelyheld in position at the end of member 22.

However, it will be appreciated that other techniques may be used tohold mandrel 20 cantilevered on member 22 while enabling free rotationthereof yet preventing relative axial movement therebetween. Forexample, bearings 32 may be suitably pressed or otherwise fixed on rodend 21 and used together with snap ring 34 and shoulder 25A to preventaxial movement of member 22 relative to support assembly 24, if desired.

The outer end portion of mandrel is radially expandable and suchradially expandable portion is supported on rotatable support 24 and isadapted to engage inside surface means of a tubular core to be carriedthereon in a manner as will be described in detail subsequently.

The outer end portion of mandrel 20 comprises a supporting memberdesignated by the numeral which has an elongated central axis designatedby the numeral at 36. Member 35 has a rod-like portion 37 comprising itsterminal inner end which is fixed to rotatable support assembly 24 sothat supporting member 35 and the members carried thereon are freelyrotatable with rotatable support assembly 24.

Rod-like portion 37 is fixed to rotatable support 24 by being fixed to acentral extension 40 of member 25. Extension 40 is substantiallycylindrical in peripheral outline and has a substantially cylindricalrecess 41 in its terminal end which is adapted to receive the terminalinner end 42 of rod-like portion 37 therewithin. Terminal inner end 42is fastened to cylindrical end portion 40 in a fixed manner by use of athreaded set screw 43, or the like.

Member 35 has a circular cross section with respect to any section takenperpendicular to axis 36 and in this example of the invention member 35is preferably substantially frusto-conical in outer peripheralconfiguration. Member 35 also has a plurality of inclined keyway meansor keyways each designated generally by the numeral 45 and in thisexample of the invention three of such inclined keyways are formed infrusto-conical member 35 is a symmetrical manner about axis 36 andspaced apart 120 degrees from each other.

Each keyway 45 has planar inclined bearing surface means or an inclinedbearing surface designated by the numeral 46. Inclined planar bearingsurfaces 46 are arranged on frusto-conical member 35 at an acute anglewith respect to axis 36.

Mandrel 20 has a plurality of three identical core support means eachdesignated generally by the numeral 49 and each carried along anassociated keyway 45. In particular each core support means is slidablycarried along an associated inclined planar bearing surface 46. Eachcore support means 49 comprises a substantially cylindrical segment 50which is suitably fastened to an associated tapered member or key 51.

Each tapered member or key 51 is substantially trapezoidal in crosssection, see FIGURE 2, and is adapted to be placed within an associatedkeyway 45 so that its bottom surface designated by the numeral 52engages and is supported on an associated planar surface 46 of a keyway45. Each tapered key 51 has fastening means shown as a threaded bolt 54which extends through an opening 55 in tapered key 51 and is threaded ina cooperating threaded opening 56 of an associated cylindrical segment50.

Each key 51 has a counterbore 60 arranged concentrically about bore 55for receiving the head 61 of an associated bolt 54 so that each assembly49 comprising a tapered -key 51 and a cylindrical segment 50 fastenedthereto may be moved along a supporting keyway 45 so that bolt 54 doesnot obstruct the sliding movement.

Thus, it is seen that a plurality of three tapered keys 51 andassociated cylindrical segments 50 are provided about the periphery offrusto-conical member 35 so as to provide a substantially continuouscylindrical outside surface which is adapted to engage inside surfacemeans of an associated tubular core designated by the numeral 63 andshown by dotted lines in the drawings. In this example, tubular core isshown as being substantially right circular cylindrical outline havingcorresponding cylindrical inside surface means designated by the numeral64.

Each cylindrical segment 50 has cooperating groove means or a groovedesignated by the numeral 65 which extends radially inwardly from itsouter periphery. Each groove 65 is provided in an associated cylindricalsegment 50 so that upon fixing each segment 50 on its associated taperedkey 51 and placing the resulting core support assembly 49 in positionabout the periphery of member 35 grooves 65 are placed in alignedrelation so as to define a substantially continuous annular groove.

Holding means comprising ring means shown as a ringlike member 66 madeof a stretchable rubber-like material is nested within aligned grooves65 and holds cylindrical segments 60 and hence support assemblies 49radially inwardly by urging such members toward axis 36 of member 35.With rubber-like ring 66 in position in its associated grooves 65 onecomponent of the radial force urging each assembly 49 against itsassociated inclined surface 46 tends to urge such assembly toward theterminal outer end of mandrel 20.

Mandrel 20 has stop means provided therein and in this example of theinvention such stop means is provided as an integral part of supportingmember 35 and comprises the terminal end face or surface designated bythe numeral 70 and defining the forward end of each keyway 45. Eachsurface 70 is adapted to receive the terminal outer end of tapered key51 thereagainst and prevent each key 51 with its fastened cylindricalsegment 50 from being moved axially outwardly beyond stop 70.

Mandrel 20 also has urging means yieldingly urging the three coresupport means 49 against stops 70. The urging means in this example ofthe invention comprises a compression spring 72 and a circular plate 73.Compression spring 72 is adapted to be placed in surrounding relationconcentrically about inner rod-like end portion 37 of frusto-conicalmember 35 and circular plate has an opening 74 therein so that it can beslid around end portion 37.

Spring 72 acts between the face 75 of cylindrical end 40 and plate 73 soas to urge plate 73 outwardly, to the left as viewed in FIGURE 4. Plate73 engages cylindrical segments 50 and keys 51 and pushes such segmentsand keys outwardly against stops 70.

The urging means comprised of spring 72 and circular plate 73 urge thecore support means 49 outwardly to a disengaged position which isillustrated in FIGURE 4 of the drawings. At such disengaged position thecore support means 49 cooperate to define a first substantiallycylindrical surface having a comparatively small first diameter. Thecore support means 49 are adapted to be engaged and pushed inwardly, tothe right as viewed in FIGURE 4, so as to cause each key 51 to ridealong its inclined planar surface 46 and thereby radially expand thecore support means 49 so that at an inward position such core supportmeans cooperate to define a second substantially cylindrical surfacewhich has a second diameter which is larger than the first diameterdefined at the disengaged position and such second cylindrical surfaceis particularly adapted to engage and support inside surface means 64 ofcore 63.

Mandrel 20 has means for engaging inside surface means of tubular core63 to provide interim holding of such tubular core during those timeintervals where core 63 must be held on mandrel 20 and the core supportmeans 49 have not been brought into engagement therewith. In thisexample of the invention such interim holding means comprises ballplunger means shown as a plurality of ball plunger assemblies 77 eachhaving a ball 80 which is normally urged outwardly by a compressionspring 81. Ball plunger assemblies 77 enable tubular core 63 to be heldon mandrel 20 for the time interval that such tubular core is picked upfrom an associated supply bin of a strip coil winding machine, forexample, and indexed into position for winding a strip conductor coilthereon.

The improved mandrel 20 of this invention has driven means provided onfrusto-conical member 35 which is adapted for connection with a suitabledrive means. The driven means of this exemplary embodiment comprises aclutch face 84 provided at the terminal end of member 35. Clutch face 84is preferably formed as. an integral part of member 35 and therebysubstantially reduces the cost of the overall mandrel in that it is notnecessary to provide a separate cooperating part which must beseparately made and assembled in position at considerably greater cost.

Mandrel is driven by any suitable standard drive means and such drivemeans has a cooperating drive face or drive clutch means whichcorresponds to and is adapted to be brought into engagement with clutchmeans 84 to rotatably drive mandrel 20.

The operation of mandrel 20 is such that as the drive means comes intoengagement with the integral clutch face 84 tubular core 63 is pushedinwardly, to the right as seen in FIGURE 4, over interim holdingassemblies 77 and against a stop shown as a shoulder 85 provided aroundthe outer end of cylindrical member comprising assembly 24. As core 63is pushed over holding assemblies 77 against stop 85 a portion of thedrive means engages the terminal outer face of the three core supportmeans 49 so as to axially move such core support means 49 alongfrusto-conical member while overriding the action of both the urgingmeans or spring 72 and the yielding holding means or rubber-like O-ring66.

The core support means 49 are preferably engaged and pushed inwardly bythe above mentioned drive means in a known manner and such support meansare also held at such inward position by such drive means. The inwardmovement of core support means 49 causes radial expansion thereof, aspreviously described, into engagement with inside surface 64 of tubularmember 63. The unique construction of mandrel 20 enables each coresupport means 49 to exert a substantially uniform holding force aboutthe periphery of inside surface 64.

The friction surface area 46 provided by each keyway is comparativelysmall, much smaller than the equivalent surface area of previousdevices, and together with the guiding of support means 49 along eachkeyway 45 assures that only a small amount of force is required to urgeeach core support means 49 axially inwardly and simultaneously radiallyoutwardly along its associated ramp surface 46. Further, the movementprovided is very smooth without sticking tendencies and hence assuresthat all core support means 49 move substantially simultaneously toprovide the above mentioned uniform clamping force.

The construction and arrangement of the various component parts ofmandrel 2% is such that mandrel 20 is easily manufactured and assembledwithout requiring special equipment. In particular the key operatingcomponents of mandrel 20 are very inexpensively produced.

Thus, the tapered keys 51 may be economically produced from rectangularbar stock. Similarly, the cylindrical segments may be produced fromright circular cylindrical members having the desired wall thickness andmerely cut as required. The keyways 45 may also be formed in any numberof inexpensive ways one of which would be to use a milling cutter to outeach keyway in frusto-conical member 35.

Likewise, the provision of driven means 84 is simply provided by thecutting of two V-shaped cuts taken in the terminal end of member 35 soas to diametrically intersect each other while being angularly spaced 90degrees from each other.

The various component parts of mandrel 20 may be made of any suitablematerial. However, each cylindrical segment or member 50 is preferablymade of plastic, steel, or the like. Also, each tapered key ispreferably made of brass. In addition, suitable surface treatment meansmay be utilized to reduce sliding friction wherever applicable.

Member 35 in this exemplary embodiment of the invention is shown as afrusto-conical member and is preferably made of hardened steel. However,member 35 may be made of any suitable material.

The outer portion of member 35 which has keyways 45 provided therein isshown as a frusto-conical member. Nevertheless, such outer peripheralconfiguration of member 35 may be of other shapes. For example, member35 may be a cylindrical member which has inclined keyways 45 providedtherein spaced degrees apart from each other in the manner illustratedso that such keyways gradually converge toward the outer end of mandrel20 and, in effect, define three planar surfaces which are identical inposition and arrangement to planar surfaces 46 and provide the sameaction. Thus, by making member 35 of cylindrical or other inexpensiveconfiguration and providing keyways 45 therein substantially identicalin size and symmetrical arrangement to keyways 45 provided in member 35the cost of mandrel can be further reduced.

Terms such as outwardly, inwardly, outer, inner, side, end, forward,right, left, and the like have been used in this disclosure of theinvention merely for ease of description and to correspond with thearrangement of component parts as illustrated in the drawings and suchterms should not be considered as limiting the scope of this inventionin any way.

Thus, it it seen that an improved expandable mandrel has been providedby this invention which is of simple and economical construction andwhich holds an associated tubular core in a more uniform manner.

While the form of the invention now preferred has been disclosed asrequired by statute, other forms may be used, all coming within thescope of the claimed subject matter which follows.

What is claimed is:

1. An expandable mandrel for carrying a tubular core comprising, asupporting member having an elongated central axis and an outer endportion which has a substantially frusto-conical configuration, drivenmeans on said supporting member for connection with a drive means saiddriven means comprising a toothed clutch face defined by substantiallyV-shapcd cutouts in the terminal small diameter and of saidfrusto-conical member, a plurality of planar inclined bearing surfacemeans symmetrically arranged on said frusto-conical portion of aidsupporting member and arranged at an acute angle with respect to saidaxis, and a plurality of core support means corresponding in number tosaid plurality of inclined bearing surface means and being yieldablyheld against said frusto-conical portion, said core support means beingengaged and axially moved along said bearing surface means to cause aradial movement thereof into engagement with inside surface means ofsaid tubular core upon engaging said driven means with said drive meansand said support means exerting a substantially uniform holding forceagainst said inside surface means following said radial movement.

2. An expandable mandrel for carrying a tubular core comprising, asupporting member having an elongated central axis, driven means on saidsupporting member for connection with a drive means, a plurality ofplanar inclined bearing surface means symmetrically arranged on saidsupporting member and arranged at an acute angle with respect to saidaxis, and a plurality of core support means corresponding in number tosaid plurality of inclined bearing surface means, each core supportmeans comprising a tapered member slidably engaging and carried on anassociated bearing surface means and comprising a substantiallycylindrical segment fastened to each tapered member, said core supportmeans being engaged and axially moved along said bearing surface meansto cause a radial movement thereof and engagement of said segments withinside surface means of sai tubular core upon engaging said driven meanswith said drive means and said segments exerting a substantially uniformholding force against said inside surface means following said radialmovement.

3. An expandable mandrel for carrying a tubular core comprising, asupporting member having an elongated central axis, driven means on saidsupporting member for connection with a drive means, a plurality ofplanar inclined bearing surface means symmetrically arranged on saidsupporting member and arranged at an acute angle with respect to saidaxis, and a plurality of core support means corresponding in number tosaid plurality of inclined bearing surface means, each core supportmeans comprising a tapered member slidably engaging and carried on anassociated bearing surface means and comprising a substantiallycylindrical segment fastened to each tapered member, said core supportmeans being engaged and axially moved along said bearing surface meansto cause a radial movement thereof and engagement of said segments withinside surface means of said tubular core upon engaging said drivenmeans with said drive means and said segments exerting a substantiallyuniform holding force against said inside surface means following saidradial movement, and said mandrel further comprising ball plunger meansfor engaging inside surface means of said tubular core to provideinterim holding of said tubular core while it is disengaged from saidcore support means.

4. An expendable mandrel for carrying a tubular core comprising, asupporting member having an elongated central axis, driven means on saidsupporting member for connection with a drive means, a plurality ofplanar inclined bearing surface means symmetrically arranged on saidsupporting member and arranged at an acute angle with respect to saidaxis, and a plurality of core support means corresponding in number ofsaid plurality of incline-d bearing surface means, each core supportmeans comprising a tapered member slidably engaging and carried on anassociated bearing surface means and comprising a substantiallycylindrical segment fastened to each tapered member, said core supportmeans being engaged and axially moved along said bearing surface meansto cause a radial movement thereof and engagement of said segments withinside surface means of said tubular core upon engaging said drivenmeans with said drive means and said segments exerting a substantiallyuniform holding force against said inside surface means following saidradial movement, and said mandrel further comprising stop means on saidsupporting member for each of said core support means, said stop meansbeing formed as an integral part of said supporting member adjacent saiddriven means, and urging means yieldingly urging said core support meansoutwardly against said stop means such that the outer periphery of saidcore support means defines a first substantially cylindrical surfacehaving a comparatively small first diameter, whereby upon engaging andaxially moving said core support means along said bearing surface meanssaid urging means is overridden to cause said radial movement of saidcore support means outwardly to define a second substantiallycylindrical surface having a second diameter larger than said firstdiameter.

5. An expandable mandrel for carrying a tubular core comprising, asupporting member having an elongated central axis, driven means on saidsupporting member for connection with a drive means, a plurality ofplanar inclined bearing surface means symmetrically arranged on saidsupporting member and arranged at an acute angle with respect to saidaxis, and a plurality of core support means corresponding in number ofsaid plurality of inclined bearing surface means, each core supportmeans comprising a tapered member slidably engaging and carried on anassociated bearing surface means and comprising a substantiallycylindrical segment fastened to each tapered member, said core supportmeans being engaged and axially moved along said bearing surface meansto cause a radial movement thereof and engagement of said segments withinside surface means of said tubular core upon engaging said drivenmeans with said drive means and said segments exerting a substantiallyuniform holding force against said inside surface means following saidradial movement, and said mandrel further comprising holding means foryieldingly radially holding said core support means against saidsupporting member, stop means on said supporting member for each of saidcore support means, said stop means being formed as an integral part ofsaid supporting member adjacent said driven means, and urging meansyieldingly urging said core support means outwardly against said stopmeans such that the outer periphery of said core support means defines afirst substantially cylindrical surface having a comparatively smallfirst diameter, whereby upon engaging and axially moving said coresupport means along said bearing surface means said urging means andholding means are overridden to cause said radial movement of said coresupport means outwardly to define a second substantially cylindricalsurface having a second diameter larger than said first diameter.

6. An expandable mandrel for carrying a tubular core comprising, asupporting member having an elongated central axis, driven means on saidsupporting member for connection with a drive means, a plurality ofsubstantially identical inclined keyway means symmetrically arranged onsaid supporting member and each having planar inclined bearing surf-acemeans and being arranged at an acute angle with respect to said axis, aplurality of core support means corresponding in number to saidplurality of keyway means, each core support means comprising a taperedkey slidably engaging and carried on an associated bearing surface meansand comprising a substantially cylindrical segment fastened to eachtapered key, said tapered keys providing a comparatively small frictionsurface enabling easy sliding of said core support means into a coresupporting position, and urging means yieldingly urging said coresupport means outwardly to a disengaged position, said core supportmeans being engaged and axially moved inwardly along said keyway meansto cause an outward radial movement thereof into engagement with insidesurface means of said tubular core upon engaging said driven means withsaid drive means and said core support means exerting a substantiallyuniform holding force against said inside surface means following saidoutward radial movement.

7. An expandable mandrel for carrying a tubular core comprising, asupporting member having an elongated central axis, driven means on saidsupporting member for connection with a drive means, a plurality ofsubstantially identical inclined keyway means symmetrically arranged onsaid supporting member and each having planar inclined bearing surfacemeans and being arranged at an acute angle with respect to said axis, aplurality of core support means corresponding in number to saidplurality of keyway means, each core support means comprising a taperedkey slidably engaging and carried on an associated bearing surface meansand comprising a substantially cylindrical segment fastened to eachtapered key, said tapered keys providing a comparatively small frictionsurface enabling easy sliding of said core support means into a coresupporting position, and urging means yieldingly urging said coresupport means outwardly to a disengaged position, said core supportmeans being engaged and axially moved inwardly along said keyway meansto cause an outward radial movement thereof into engagement with insidesurface means of said tubular core upon engaging said driven means withsaid drive means and said core support means exerting a substantiallyuniform holding force against said inside surface means following saidoutward radial movement, and said mandrel further comprising stop meanson said supporting member for each of said core support means, said stopmeans being formed as an integral part of said supporting memberadjacent said driven means, and said urging means yieldingly urging saidcore support means outwardly against said stop means to define saiddisengaged position.

8. A mandrel as set forth in claim 7 further comprising ball plungermeans for engaging inside surface means of said tubular core to provideinterim holding of said tubular core while it is disengaged from saidcore support means.

9. A mandrel as set forth in claim 7 in Which the outer end portion ofsaid supporting member is of circular cross section and said keywaymeans are provided in said outer end portion.

10. A mandrel as set forth in claim 9 in which said supporting memberhas an inner rod-like portion which has its terminal inner end fixed toa freely rotatably supsion spring means acting between said rotatablesupport and said core support means.

References Cited UNITED STATES PATENTS 576,677 2/ 1897 Kenworthy242--72.1 1,192,063 7/1916 Hoberg 24272.1 2,952,418 9/ 1960 Rice 24272.13,331,565 7/ 1967 Gerritts 24272.1

port therefor and said urging means comprises comprese 10 NATHAN L.MINTZ, Primary Examiner.

